From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0A09ECDE43 for ; Fri, 19 Oct 2018 05:00:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F0A72145D for ; Fri, 19 Oct 2018 05:00:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mIF+7pkE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F0A72145D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727245AbeJSNFV (ORCPT ); Fri, 19 Oct 2018 09:05:21 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:42670 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726478AbeJSNFU (ORCPT ); Fri, 19 Oct 2018 09:05:20 -0400 Received: by mail-pf1-f193.google.com with SMTP id f26-v6so15927603pfn.9 for ; Thu, 18 Oct 2018 22:00:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=zH1B+xgskiRAT5rePx+9xDVnmVM332/H+OPze+6IO8M=; b=mIF+7pkE+wr9lXdJ8VZ/A1XiWXaygWgjgn2ODpz76BjD7bGiMG0j/dLaRqct8Y3ym2 7GE43WxFkKeiueEB/gULfyANzeNe+CrnedE4pN1NsNg5RgdmQlIT5jIZeK9hQDdisD3a Oi6ckYeb7a0X2WY2yJzhmKoIG4YDqvtFlGGQJojgxRDs6viojtv6l0KWaNwo0rkYL3Go bnvYwzBaqbzYheQb6dyCnQxd9eNkAfpUIZQMv4dd65BobvhIY7N+3/nW/qqbsuKy9sz/ aBIUWM2FJRJmiOm4T8c5Zb+K/43X66WrZmw61HVBqJ1UtOsweMVOEFi0C4s6Josi00+e a9+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=zH1B+xgskiRAT5rePx+9xDVnmVM332/H+OPze+6IO8M=; b=tuBw/2codle+mYtpfIfBoSnrSIvoBVIxN+SrGFA65I9WhAAZWYkANDanEz286TbP8c RYAFCPl4usAc4naR7EC/O6t34DfWnxYCwMW2TA/HPmun/qBvpmwVLUvrNp0MGs0eIUrG OdOIRFNE1v6ljg1nqnIYi58uU5x7H0VWeY8Kfn75+JjiNLmYOQ2p8L67uMPs54i7Z88H pU06FdbE//myMidRMYMhXQQuvrE+uJh1/T5fxnyOdGboecgHT4BLus8DEBrT6RUWYNea pIfHH3F0DQn7EC1XQDUzg9dNJYCwWjj8MIKWreC1n+/LZbRuE9oRe7Bamii3oDr/G1+M lXbg== X-Gm-Message-State: ABuFfojOx6jq0y9rY+rrmZqmUHkcixOuTMg12HDDgWxBszZE7rwSroNQ d/CeTFNxDHB11BqJo3cC2yU= X-Google-Smtp-Source: ACcGV63djeapbjuMqyAqh1aNlW9o02l9oInXubQKuYTJwfyicwVnkJ4YIlaeY/r80bBSUaq/LDVc2w== X-Received: by 2002:a62:2e02:: with SMTP id u2-v6mr34184042pfu.134.1539925256202; Thu, 18 Oct 2018 22:00:56 -0700 (PDT) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:180::1:8c1d]) by smtp.gmail.com with ESMTPSA id q2-v6sm37402955pfc.17.2018.10.18.22.00.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Oct 2018 22:00:55 -0700 (PDT) Date: Thu, 18 Oct 2018 22:00:53 -0700 From: Alexei Starovoitov To: Andy Lutomirski Cc: Nadav Amit , Oleg Nesterov , Ingo Molnar , Peter Zijlstra , "H. Peter Anvin" , Thomas Gleixner , LKML , X86 ML , Borislav Petkov , "Woodhouse, David" , daniel@iogearbox.net, guro@fb.com Subject: Re: [RFC PATCH 1/5] x86: introduce preemption disable prefix Message-ID: <20181019050051.bs2kk4sagu7hpwxx@ast-mbp.dhcp.thefacebook.com> References: <20181018005420.82993-1-namit@vmware.com> <20181018005420.82993-2-namit@vmware.com> <07255D2B-0243-4254-B62A-37050C44207E@vmware.com> <925F22EA-F8CB-4194-B96B-378409ED7918@vmware.com> <2626124E-7344-42F3-AD07-0BB34D62A9EE@amacapital.net> <6F1FD9DA-5E86-42A2-8EAF-05F5D70FE2EF@vmware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180223 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > > > > Another example is __BPF_PROG_RUN_ARRAY(), which also uses > > preempt_enable_no_resched(). > > Alexei, I think this code is just wrong. why 'just wrong' ? > Do you know why it uses > preempt_enable_no_resched()? dont recall precisely. we could be preemptable at the point where macro is called. I think the goal of no_resched was to avoid adding scheduling points where they didn't exist before just because a prog ran for few nsec. May be Daniel or Roman remember.